1. Field of the Invention
The present invention resides in the field of a medical apparatus, and more particularly to a blood letting apparatus adapted for self-administration.
Some medical conditions, by way of example diabetes, require that the patient be tested for blood content, and particularly blood sugar content. In the case of a diabetic patient, at the early stages of insulin therapy it is necessary, in order to determine the proper insulin dosages, that blood samples be tested many times a day.
Numerous systems for patient self-monitoring of blood glucose levels have been developed. However, in each such system it is necessary for the patient or for an attendant to draw blood.
2. The Prior Art
Numerous devices have been employed for the drawing of the small quantities of blood necessary for effecting blood glucose level testing.
In my U.S. Pat. Nos. 2,801,633 and 3,046,987 there are disclosed various forms of an improved lancet member which enable the drawing of blood samples with minimal trauma to the patient and minimal admixture of tissue fluids, which latter tend prematurely to coagulate the blood and by admixing with the blood to give misleading or inaccurate readings.
The procedure of self blood letting by stabbing with a lancet or like piercing instrument, even using the improved lancets described in my above mentioned patents, presents a difficult task to the patient. There is a natural tendency for the patient to flinch, with the result that the desired clean wound will not be produced or that the lancet will not enter the skin in a perpendicular orientation. In addition, it is not unusual for an inexperienced patient to fail to insert the lancet through the dermal layers, with the result that the procedure must be repeated.
In order to minimize the manipulative procedures involved in a self-stabbing procedure, mechanical devices have been constructed which perform the stabbing task. Such devices typically employ a spring biased plunger which carries a sharpened end. The devices are used by cocking the plunger and positioning the distal portion of the device against the skin to be pierced, following which the plunger is released. The plunger will carry the lancet tip to a preset depth into the tissue of the patient.
The use of the devices of the type described has been found to be painful and to induce substantial trauma in the areas surrounding the puncture. It has been theorized that the trauma and pain are engendered in large measure by the speed at which the lancet is travelling when the wound is effected.